Index structure for blockchain ledger

ABSTRACT

An example operation may include one or more of storing an index structure that comprises an index of keys from a blockchain ledger, where the keys are stored as nodes in the index structure, receiving a blockchain request for data stored on the blockchain ledger, reading a set of keys of a non-critical query included in the blockchain request from the nodes in the index structure, and generating and storing a read set for the blockchain request which does not include values for the set of keys of the non-critical query.

TECHNICAL FIELD

This application generally relates to storing data via a blockchain, andmore particularly, to an index structure which stores key values fromthe blockchain ledger and which can be accessed for non-critical queriesto reduce phantom data items.

BACKGROUND

A centralized database stores and maintains data in a single database(e.g., a database server) at one location. This location is often acentral computer, for example, a desktop central processing unit (CPU),a server CPU, or a mainframe computer. Information stored on acentralized database is typically accessible from multiple differentpoints. Multiple users or client workstations can work simultaneously onthe centralized database, for example, based on a client/serverconfiguration. A centralized database is easy to manage, maintain, andcontrol, especially for purposes of security because of its singlelocation. Within a centralized database, data redundancy is minimized asa single storing place of all data also implies that a given set of dataonly has one primary record.

Meanwhile, blockchain systems store data on an immutable ledger, providedistributed and decentralized access to the immutable ledger throughnon-trusting participants, establish consensus requirements foragreement between the non-trusting participants such that no one entitycan change the immutable ledger without agreement from others, invokesmart contracts, and the like. A blockchain is formed by a network ofparticipants which agree to add a block (with data stored therein) tothe immutable ledger. Before being added, the block is linked to aprevious block on the immutable ledger thereby forming a chain. Thisimmutable and incorruptible nature of blockchain makes it safe fromfalsified information and hacks. The decentralized nature also gives itthe unique quality of being trustless, in that parties do not need toestablish trust before they can transact safely. Through blockchain, newand improved opportunities for data storage, communication, and securityare emerging.

SUMMARY

One example embodiment provides an apparatus that includes one or moreof a storage configured to store an index structure that comprises anindex of keys from a blockchain ledger, where the keys are stored asnodes in the index structure, and a processor configured to one or moreof receive a blockchain request for data stored on the blockchainledger, read a set of keys of a non-critical query included in theblockchain request from the nodes in the index structure, and generateand store a read set for the blockchain request which does not includevalues for the set of keys of the non-critical query.

Another example embodiment provides a method that includes one or moreof storing an index structure that comprises an index of keys from ablockchain ledger, where the keys are stored as nodes in the indexstructure, receiving a blockchain request for data stored on theblockchain ledger, reading a set of keys of a non-critical queryincluded in the blockchain request from the nodes in the indexstructure, and generating and storing a read set for the blockchainrequest which does not include values for the set of keys of thenon-critical query.

A further example embodiment provides a non-transitory computer readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform one or more of storing an index structure thatcomprises an index of keys from a blockchain ledger, where the keys arestored as nodes in the index structure, receiving a blockchain requestfor data stored on the blockchain ledger, reading a set of keys of anon-critical query included in the blockchain request from the nodes inthe index structure, and generating and storing a read set for theblockchain request which does not include values for the set of keys ofthe non-critical query.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram illustrating a blockchain network implementing abinary index structure according to example embodiments.

FIG. 1B is a diagram illustrating an example of the binary indexstructure of FIG. 1A, according to example embodiments.

FIG. 2A is a diagram illustrating an example blockchain architectureconfiguration, according to example embodiments.

FIG. 2B is a diagram illustrating a blockchain transactional flow amongnodes, according to example embodiments.

FIG. 3A is a diagram illustrating a permissioned network, according toexample embodiments.

FIG. 3B is a diagram illustrating another permissioned network,according to example embodiments.

FIG. 3C is a diagram illustrating a permissionless network, according toexample embodiments.

FIG. 4A is a diagram illustrating a process of querying a blockchainledger via a range query according to example embodiments.

FIG. 4B is a diagram illustrating a process of querying an indexstructure on top of a blockchain ledger according to exampleembodiments.

FIG. 5 is a diagram illustrating a method of accessing an indexstructure on top of a blockchain ledger according to exampleembodiments.

FIG. 6A is a diagram illustrating an example system configured toperform one or more operations described herein, according to exampleembodiments.

FIG. 6B is a diagram illustrating another example system configured toperform one or more operations described herein, according to exampleembodiments.

FIG. 6C is a diagram illustrating a further example system configured toutilize a smart contract, according to example embodiments.

FIG. 6D is a diagram illustrating yet another example system configuredto utilize a blockchain, according to example embodiments.

FIG. 7A is a diagram illustrating a process of a new block being addedto a distributed ledger, according to example embodiments.

FIG. 7B is a diagram illustrating data contents of a new data block,according to example embodiments.

FIG. 7C is a diagram illustrating a blockchain for digital content,according to example embodiments.

FIG. 7D is a diagram illustrating a block which may represent thestructure of blocks in the blockchain, according to example embodiments.

FIG. 8A is a diagram illustrating an example blockchain which storesmachine learning (artificial intelligence) data, according to exampleembodiments.

FIG. 8B is a diagram illustrating an example quantum-secure blockchain,according to example embodiments.

FIG. 9 is a diagram illustrating an example system that supports one ormore of the example embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined or removed in any suitablemanner in one or more embodiments. For example, the usage of the phrases“example embodiments”, “some embodiments”, or other similar language,throughout this specification refers to the fact that a particularfeature, structure, or characteristic described in connection with theembodiment may be included in at least one embodiment. Thus, appearancesof the phrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined orremoved in any suitable manner in one or more embodiments. Further, inthe diagrams, any connection between elements can permit one-way and/ortwo-way communication even if the depicted connection is a one-way ortwo-way arrow. Also, any device depicted in the drawings can be adifferent device. For example, if a mobile device is shown sendinginformation, a wired device could also be used to send the information.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof networks and data. Furthermore, while certain types of connections,messages, and signaling may be depicted in exemplary embodiments, theapplication is not limited to a certain type of connection, message, andsignaling.

Example embodiments provide methods, systems, components, non-transitorycomputer readable media, devices, and/or networks, which implement anindex structure that is logically on top of a blockchain ledger andwhich prevents non-critical phantom items from occurring during ablockchain transaction.

In one embodiment, the application utilizes a decentralized database(such as a blockchain) that is a distributed storage system, whichincludes multiple nodes that communicate with each other. Thedecentralized database includes an append-only immutable data structureresembling a distributed ledger capable of maintaining records betweenmutually untrusted parties. The untrusted parties are referred to hereinas peers or peer nodes. Each peer maintains a copy of the databaserecords and no single peer can modify the database records without aconsensus being reached among the distributed peers. For example, thepeers may execute a consensus protocol to validate blockchain storagetransactions, group the storage transactions into blocks, and build ahash chain over the blocks. This process forms the ledger by orderingthe storage transactions, as is necessary, for consistency. In variousembodiments, a permissioned and/or a permissionless blockchain can beused. In a public or permission-less blockchain, anyone can participatewithout a specific identity. Public blockchains can involve nativecryptocurrency and use consensus based on various protocols such asProof of Work (PoW). On the other hand, a permissioned blockchaindatabase provides secure interactions among a group of entities whichshare a common goal but which do not fully trust one another, such asbusinesses that exchange funds, goods, information, and the like.

The application can utilize a blockchain that operates arbitrary,programmable logic, tailored to a decentralized storage scheme andreferred to as “smart contracts” or “chaincodes.” In some cases,specialized chaincodes may exist for management functions and parameterswhich are referred to as system chaincode. The application can furtherutilize smart contracts that are trusted distributed applications whichleverage tamper-proof properties of the blockchain database and anunderlying agreement between nodes, which is referred to as anendorsement or endorsement policy. Blockchain transactions associatedwith this application can be “endorsed” before being committed to theblockchain while transactions, which are not endorsed, are disregarded.An endorsement policy allows chaincode to specify endorsers for atransaction in the form of a set of peer nodes that are necessary forendorsement. When a client sends the transaction to the peers specifiedin the endorsement policy, the transaction is executed to validate thetransaction. After validation, the transactions enter an ordering phasein which a consensus protocol is used to produce an ordered sequence ofendorsed transactions grouped into blocks.

This application can utilize nodes that are the communication entitiesof the blockchain system. A “node” may perform a logical function in thesense that multiple nodes of different types can run on the samephysical server. Nodes are grouped in trust domains and are associatedwith logical entities that control them in various ways. Nodes mayinclude different types, such as a client or submitting-client nodewhich submits a transaction-invocation to an endorser (e.g., peer), andbroadcasts transaction-proposals to an ordering service (e.g., orderingnode). Another type of node is a peer node which can receive clientsubmitted transactions, commit the transactions and maintain a state anda copy of the ledger of blockchain transactions. Peers can also have therole of an endorser, although it is not a requirement. Anordering-service-node or orderer is a node running the communicationservice for all nodes, and which implements a delivery guarantee, suchas a broadcast to each of the peer nodes in the system when committingtransactions and modifying a world state of the blockchain, which isanother name for the initial blockchain transaction which normallyincludes control and setup information.

This application can utilize a ledger that is a sequenced,tamper-resistant record of all state transitions of a blockchain. Statetransitions may result from chaincode invocations (i.e., transactions)submitted by participating parties (e.g., client nodes, ordering nodes,endorser nodes, peer nodes, etc.). Each participating party (such as apeer node) can maintain a copy of the ledger. A transaction may resultin a set of asset key-value pairs being committed to the ledger as oneor more operands, such as creates, updates, deletes, and the like. Theledger includes a blockchain (also referred to as a chain) which is usedto store an immutable, sequenced record in blocks. The ledger alsoincludes a state database which maintains a current state of theblockchain.

This application can utilize a chain that is a transaction log which isstructured as hash-linked blocks, and each block contains a sequence ofN transactions where N is equal to or greater than one. The block headerincludes a hash of the block's transactions, as well as a hash of theprior block's header. In this way, all transactions on the ledger may besequenced and cryptographically linked together. Accordingly, it is notpossible to tamper with the ledger data without breaking the hash links.A hash of a most recently added blockchain block represents everytransaction on the chain that has come before it, making it possible toensure that all peer nodes are in a consistent and trusted state. Thechain may be stored on a peer node file system (i.e., local, attachedstorage, cloud, etc.), efficiently supporting the append-only nature ofthe blockchain workload.

The current state of the immutable ledger may be stored in a statedatabase, and may represent the latest values for all keys that areincluded in the chain transaction log. Since the current staterepresents the latest key values known to a channel, it is sometimesreferred to as a world state. Chaincode invocations execute transactionsagainst the current state data of the ledger. To make these chaincodeinteractions efficient, the latest values of the keys may be stored in astate database. The state database may be simply an indexed view intothe chain's transaction log, it can therefore be regenerated from thechain at any time. The state database may automatically be recovered (orgenerated if needed) upon peer node startup, and before transactions areaccepted.

Before data may be added to a distributed database such as blockchain, aconsensus protocol must be performed to ensure the data is agreed upon.This form of decentralized agreement enables blockchain to be managedwithout a central/controlling entity. In Hyperledger Fabric, theconsensus protocol has various phases including endorsement, ordering,and validation/commitment. During an endorsement phase, a subset ofblockchain peers simulate a transaction to ensure the transaction can beprocessed based on the current state of the blockchain (stored on ablockchain ledger). However, no data is added to the blockchain at thispoint. If endorsed, the transaction is sent to an orderer node whichaggregates endorsed transactions into a data block. The orderer nodethen cuts the data block when it is full and broadcasts the data blockto blockchain peers on that channel. The blockchain peers thenre-execute the transactions based on the current state of the blockchainto ensure that data is still valid. If approved, the transactions areused to update the state of the ledger and the data block is stored onthe blockchain.

To provide proof of the endorsement phase, endorser nodes will generatea read set that identifies the key values that are read from theblockchain ledger and a write set that identifies values to be writtento the blockchain ledger. When the transactions are subsequentlycommitted by a blockchain peer during the validation/commitment phase,the read set is re-run at commit time. If the result is different fromproposal/endorsement time, a phantom read error is thrown. This checkensures that the state and environment has not been changed fromproposal time to commit time. However, the read set is only evaluatedduring range queries and is the result of the range query performed byHyperledger Fabric. A phantom read error from non-critical range queriescan be a huge obstacle for performance of smart contract logic becausephantom read errors cause a transaction to be denied.

In many cases, a transaction can run multiple range queries and not allrange queries are critical to evaluate endorsement. In the cases where arange query is not critical to the evaluation, there is no need for apeer to check for phantom read errors. However, the current framework ofblockchain solutions such as Hyperledger Fabric do not provide a way toavoid execution of range queries. Due to this limitation, sometransactions fail even though they should succeed. Such failureseliminate the possibility of running concurrent transactions that makethe same non-critical range queries.

The example embodiments overcome the deficiencies in related blockchainsolutions by building an index structure on top of the blockchain ledgerand enabling blockchain peers to query the index structure instead ofrange-querying the blockchain ledger. In some embodiments, the indexstructure is a binary tree where keys are stored as nodes that areconnected to each other via links. The index structure may include ahierarchical format and nodes/keys may be connected to each other basedon any desired business rules. When a blockchain transaction isreceived, a blockchain peer may endorse the transaction by reading keysfor non-critical queries from the index structure instead of theblockchain ledger. In doing so, when the endorsing peer generates a readset for the transaction, the blockchain peer can omit the data read fromthe index structure. Accordingly, when a committing peer re-runs thequeries at commit time, the committing peer may also read the keys fornon-critical queries from the index structure, and avoid performing acomparison of the non-critical data. Thus, phantom read errors fornon-critical items can be avoided.

The index may be structured as a binary search tree that is logically ontop of the blockchain ledger and which allows transactions to bypassphantom or checks for non-critical range queries. The benefits of theexample embodiments include significant improvement in chaincodeperformance by allowing developers to implement concurrent smartcontract logic. Furthermore, transaction throughput is also improvedbecause transactions are no longer denied due to phantom items ofnon-critical transactional data. The system still allows for criticalrange queries to be processed off of the ledger. Therefore, phantom readerrors can be checked for critical range queries.

FIG. 1A illustrates a blockchain network 100 implementing an indexstructure 130 on top of a blockchain ledger 120, according to exampleembodiments. Referring to FIG. 1A, a plurality of blockchain peers121-125 share in management of a blockchain (not shown). The blockchainmay include a chain of blocks that are hash-linked together on theblockchain ledger 120. The blockchain ledger 120 may also store a statedatabase (referred to herein as a world state) which includes thecurrent values of all keys (unique data items) stored on the blockchain.In a typical transaction from a client 110, a blockchain peer wouldendorse the transaction based on key-values obtained from the statedatabase of the blockchain ledger 120.

Meanwhile, in the example embodiments, the blockchain peers 121-125 maybuild and maintain an index structure 130 on top of the blockchainledger 120. The index structure 130 may include an index of keys fromthe blockchain ledger 130 which are ordered/connected based on businesslogic defined by the system. When a blockchain request (such as atransaction) is received from client 110, non-critical queries of theblockchain request may be processed using the index structure 130 whilecritical queries can still be processed from key values on theblockchain ledger 120.

In FIG. 1A, the client 110 has chosen blockchain peers 123 and 124 to beendorsing peers for a transaction. Each of these blockchain peers 123and 124 may simulate the transaction by invoking chaincode(deployed/packaged smart contract logic) which reads data from theblockchain ledger 120 to verify whether the transaction will besuccessful. To endorse the transaction, the blockchain peer 123 may runa plurality of range queries which retrieve data from the blockchainledger 120. According to various embodiments, the blockchain peer 123may identify one or more range queries that are not critical to theendorsement (i.e., they do not affect the transactions validity) andquery the index structure 130 for the keys of such query. When theblockchain peer 123 generates a read set for the endorsement, theblockchain peer 123 may include all of the keys that are read from theblockchain ledger 120 (critical range queries) and omit the keys thatare read from the index structure 130 (non-critical queries).

The resulting read set may be returned to the client 110 and forward toan ordering node (not shown) for inclusion in the blockchain. When adata block including the transaction (and its read set) is cut and sentto the blockchain peers 121-125, each of the blockchain peers 121-125may again perform the queries to validate the transaction beforecommitting the block to its local copy of the blockchain ledger 120.Here, the blockchain peers 121-125 may query the blockchain ledger 120for critical range queries, and compare the key values read from theblockchain ledger 120 to the key values stored in the read set of thetransaction. However, for non-critical queries, the blockchain peers121-125 may query their own copy of the index structure 130 withouthaving to perform a validation of the non-critical queries. As a result,phantom read errors for non-critical data/queries can be avoided.

FIG. 1B illustrates an example of the index structure 130 of FIG. 1A,according to example embodiments. Referring to FIG. 1B, chaincoderunning on a blockchain peer may build the index structure 130 on top ofthe blockchain ledger 120 to create a custom index for less error-pronequeries. In this example, the index structure 130 is a binary tree. Theindex structure 130 may be part of the smart contract logic that ispackaged into chaincode that is deployed and executed by the blockchainpeers 121-125 shown in FIG. 1A.

A range query uses a range iterator to go over a set of ledger keys inthe blockchain ledger 120. The iterator can be used to iterate over allkeys between a start key and an end key within the range. Each key has avalue associated with it. The peers use range queries to get a range ofvalues. A phantom Read error occurs if two query executions renderdifferent results. For example, if a range query executed during anendorsement of a transaction and the same range query executed during avalidation/commitment of the transaction result in different keys/valuesbeing returned, a phantom error is detected A phantom error can becaused by a concurrent transaction modifying a key(s) within the rangeof records in between the endorsement and the validation/commitment.

In the example embodiments, the index structure 130 persists betweentransactions. It is an alternative way to store ledger keys rather thansimply storing keys in the blockchain ledger 120 database. In FIG. 1B,the keys are stored as nodes 132 in the index structure. Furthermore,the keys/nodes 132 are linked with links 134 in the binary tree. Eachnode 132 in the index structure 130 corresponds to a key value stored onthe blockchain ledger 120, as denoted by the arrows in FIG. 1B. Theblockchain ledger 120 may store key-value pairs which include a key(e.g., system value) and a timestamp at which the key was added to thesystem. Each ledger key corresponds to a node in the index structure130. Furthermore, each key node's next property points to another key.The keys may be sorted in the index structure 130 at insertion based onbusiness logic within the smart contract of the blockchain peer.

To query the index structure 130, the blockchain peer may read the keysone by one as nodes in the tree instead of querying them by range on theblockchain ledger 120. In the example of a binary search tree as theindex structure 130, the blockchain peer can identify the next node 132in the index structure 130 by calling a Next( ). This functionidentifies an order among the keys within the index structure 130. Theblockchain peer will not generate a phantom read error by simplyquerying the next node. Some phantom read errors are valid as certaindata should not be modified within the same read-write set. These dataitems may be still be queried from the blockchain ledger 120. However,other phantom read errors are due to changes in data that is notcritical to the transaction's validity. The example embodiments providean innovative way to avoid phantom read errors that are not critical byquerying the index structure 130 and not adding the results to a readset.

Without the custom index structure built by the example embodiments,running range queries (such as by using Fabric's GetStateByRangefunction) with an iterator is the only way for the blockchain peer tounderstand what the next key is. So if any key within the range isadded, updated, or deleted between proposal and commit time,GetStateByRange would return different results and the phantom readerror would occur. In contrast, instead of reading keys in a rangequery, the example embodiments read individual elements in the range oneby one using an index structure such as a binary search tree. With abinary search tree, the blockchain peer can identify the next key is bycalling Next( ). By eliminating the need for the ledger's native rangequery function, the embodiments create a way to eliminate non-criticalphantom read checks to allow better chaincode performance.

Blockchain, i.e. Hyperledger Fabric, has the following functions (orsimilar) to save and query ledger data. Ledger data is typically savedas a key-value pair. For example, PutState(k,v) is a function to storevalue v in the ledger with key k. GetState(k) is a function to get avalue stored in the ledger for the key k. This query is not added to theread set of transaction during a phantom read error check.GetStateByRange(startKey, endKey) is a function to query ledger databetween start key (inclusive) and end key (exclusive). This range queryis added to the read set of transaction during a phantom read errorcheck.

Meanwhile, the index structure (e.g., a binary search tree, red-blacktree, etc.) provides the following functions to add a node or find anode in the binary tree. In this example, the node values in the binarysearch tree represent ledger keys. For example, Insert(k) may insert thekey k to the binary search tree and rebalance if needed. Find(k) mayfind a node in the binary search tree whose key is greater than or equalto input key value k. Next(k) may receive the current node k in thebinary search tree, and return the next key k+1 in the binary searchtree. The order of the keys in the index structure may be based onbusiness logic implemented within the smart contract.

Furthermore, the example embodiments enable a peer to build an index ofthe ledger keys using a binary search tree on top of the ledger. When apiece of data (key-value pair) is added to the blockchain ledger, theblockchain peer may use the following logic instead of usingblockchain's native PutState( ) function.

PutStateBST (k, v) {

-   -   Insert(k)    -   PutState(k, v)

}

In this example, before adding the data to the ledger, the peer may addthe key to the binary search tree in order to build an index of ledgerkeys. In order to bypass a phantom read error check for non-criticalrange queries, the blockchain peer may use the binary search tree indexto query a range of data using the following logic instead ofBlockchain's native GetStateByRange( ) function. The following functionuses the binary search tree index in order to find the next key to read,and then reads each value from the ledger individually using the nativeGetState( ) function. This avoids adding a read set for phantom readerror checking.

RangeQueryBST(sk, ek) { result = [ ] n = Find(sk) while ( n < ek ) { v =GetState(n) result = append(result, v) n = Next(n) } return result }

FIG. 2A illustrates a blockchain architecture configuration 200,according to example embodiments. Referring to FIG. 2A, the blockchainarchitecture 200 may include certain blockchain elements, for example, agroup of blockchain nodes 202. The blockchain nodes 202 may include oneor more nodes 204-210 (these four nodes are depicted by example only).These nodes participate in a number of activities, such as blockchaintransaction addition and validation process (consensus). One or more ofthe blockchain nodes 204-210 may endorse transactions based onendorsement policy and may provide an ordering service for allblockchain nodes in the architecture 200. A blockchain node may initiatea blockchain authentication and seek to write to a blockchain immutableledger stored in blockchain layer 216, a copy of which may also bestored on the underpinning physical infrastructure 214. The blockchainconfiguration may include one or more applications 224 which are linkedto application programming interfaces (APIs) 222 to access and executestored program/application code 220 (e.g., chaincode, smart contracts,etc.) which can be created according to a customized configurationsought by participants and can maintain their own state, control theirown assets, and receive external information. This can be deployed as atransaction and installed, via appending to the distributed ledger, onall blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers ofblockchain data, services (e.g., cryptographic trust services, virtualexecution environment, etc.), and underpinning physical computerinfrastructure that may be used to receive and store new transactionsand provide access to auditors which are seeking to access data entries.The blockchain layer 216 may expose an interface that provides access tothe virtual execution environment necessary to process the program codeand engage the physical infrastructure 214. Cryptographic trust services218 may be used to verify transactions such as asset exchangetransactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process andexecute program/application code 220 via one or more interfaces exposed,and services provided, by blockchain platform 212. The code 220 maycontrol blockchain assets. For example, the code 220 can store andtransfer data, and may be executed by nodes 204-210 in the form of asmart contract and associated chaincode with conditions or other codeelements subject to its execution. As a non-limiting example, smartcontracts may be created to execute reminders, updates, and/or othernotifications subject to the changes, updates, etc. The smart contractscan themselves be used to identify rules associated with authorizationand access requirements and usage of the ledger. For example, the smartcontract (or chaincode executing the logic of the smart contract) mayread blockchain data 226 from an index structure. The blockchain datamay be processed by one or more processing entities (e.g., virtualmachines) included in the blockchain layer 216 to generate results 228of the chaincode invocation. The results may be determined by thebusiness logic within the smart contract. The physical infrastructure214 may be utilized to retrieve any of the data or information describedherein.

A smart contract may be created via a high-level application andprogramming language, and then written to a block in the blockchain. Thesmart contract may include executable code which is registered, stored,and/or replicated with a blockchain (e.g., distributed network ofblockchain peers). To be deployed, the smart contract may be packagedinto chaincode (with other smart contracts) and deployed onto ablockchain peer. A transaction is an execution of the smart contractcode which can be performed in response to conditions associated withthe smart contract being satisfied. The executing of the smart contractmay trigger a trusted modification(s) to a state of a digital blockchainledger. The modification(s) to the blockchain ledger caused by the smartcontract execution may be automatically replicated throughout thedistributed network of blockchain peers through one or more consensusprotocols.

The smart contract may write data to the blockchain in the format ofkey-value pairs. Furthermore, the smart contract code can read thevalues stored in a blockchain and use them in application operations.The smart contract code can write the output of various logic operationsinto one or more blocks within the blockchain. The code may be used tocreate a temporary data structure in a virtual machine or othercomputing platform. Data written to the blockchain can be public and/orcan be encrypted and maintained as private. The temporary data that isused/generated by the smart contract is held in memory by the suppliedexecution environment, then deleted once the data needed for theblockchain is identified.

A chaincode may include the code interpretation of a smart contract,with additional features. Here, the chaincode may include a packaged anddeployable version of the logic within the smart contract. As describedherein, the chaincode may be program code deployed on a computingnetwork, where it is executed and validated by chain validators togetherduring a consensus process. The chaincode receives a hash and retrievesfrom the blockchain a hash associated with the data template created byuse of a previously stored feature extractor. If the hashes of the hashidentifier and the hash created from the stored identifier template datamatch, then the chaincode sends an authorization key to the requestedservice. The chaincode may write to the blockchain data associated withthe cryptographic details.

FIG. 2B illustrates an example of a blockchain transactional flow 250between nodes of the blockchain in accordance with an exampleembodiment. Referring to FIG. 2B, the transaction flow may include aclient node 260 transmitting a transaction proposal 291 to an endorsingpeer node 281. The endorsing peer 281 may verify the client signatureand execute a chaincode function to initiate the transaction. The outputmay include the chaincode results, a set of key/value versions that wereread in the chaincode (read set), and the set of keys/values that werewritten in chaincode (write set). Here, the endorsing peer 281 maydetermine whether or not to endorse the transaction proposal. Theproposal response 292 is sent back to the client 260 along with anendorsement signature, if approved. The client 260 assembles theendorsements into a transaction payload 293 and broadcasts it to anordering service node 284. The ordering service node 284 then deliversordered transactions as blocks to all peers 281-283 on a channel. Beforecommittal to the blockchain, each peer 281-283 may validate thetransaction. For example, the peers may check the endorsement policy toensure that the correct allotment of the specified peers have signed theresults and authenticated the signatures against the transaction payload293.

Referring again to FIG. 2B, the client node initiates the transaction291 by constructing and sending a request to the peer node 281, which isan endorser. The client 260 may include an application leveraging asupported software development kit (SDK), which utilizes an availableAPI to generate a transaction proposal. The proposal is a request toinvoke a chaincode function so that data can be read and/or written tothe ledger (i.e., write new key value pairs for the assets). The SDK mayserve as a shim to package the transaction proposal into a properlyarchitected format (e.g., protocol buffer over a remote procedure call(RPC)) and take the client's cryptographic credentials to produce aunique signature for the transaction proposal.

In response, the endorsing peer node 281 may verify (a) that thetransaction proposal is well formed, (b) the transaction has not beensubmitted already in the past (replay-attack protection), (c) thesignature is valid, and (d) that the submitter (client 260, in theexample) is properly authorized to perform the proposed operation onthat channel. The endorsing peer node 281 may take the transactionproposal inputs as arguments to the invoked chaincode function. Thechaincode is then executed against a current state database to producetransaction results including a response value, read set, and write set.However, no updates are made to the ledger at this point. In 292, theset of values, along with the endorsing peer node's 281 signature ispassed back as a proposal response 292 to the SDK of the client 260which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies theendorsing peers signatures and compares the proposal responses todetermine if the proposal response is the same. If the chaincode onlyqueried the ledger, the application would inspect the query response andwould typically not submit the transaction to the ordering node service284. If the client application intends to submit the transaction to theordering node service 284 to update the ledger, the applicationdetermines if the specified endorsement policy has been fulfilled beforesubmitting (i.e., did all peer nodes necessary for the transactionendorse the transaction). Here, the client may include only one ofmultiple parties to the transaction. In this case, each client may havetheir own endorsing node, and each endorsing node will need to endorsethe transaction. The architecture is such that even if an applicationselects not to inspect responses or otherwise forwards an unendorsedtransaction, the endorsement policy will still be enforced by peers andupheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assemblesendorsements into a transaction proposal and broadcasts the transactionproposal and response within a transaction message to the ordering node284. The transaction may contain the read/write sets, the endorsingpeers signatures and a channel ID. The ordering node 284 does not needto inspect the entire content of a transaction in order to perform itsoperation, instead the ordering node 284 may simply receive transactionsfrom all channels in the network, order them chronologically by channel,and create blocks of transactions per channel.

The blocks are delivered from the ordering node 284 to all peer nodes281-283 on the channel. The data section within the block may bevalidated to ensure an endorsement policy is fulfilled and to ensurethat there have been no changes to ledger state for read set variablessince the read set was generated by the transaction execution.Furthermore, in step 295 each peer node 281-283 appends the block to thechannel's chain, and for each valid transaction the write sets arecommitted to current state database. An event may be emitted, to notifythe client application that the transaction (invocation) has beenimmutably appended to the chain, as well as to notify whether thetransaction was validated or invalidated.

FIG. 3A illustrates an example of a permissioned blockchain network 300,which features a distributed, decentralized peer-to-peer architecture.In this example, a blockchain user 302 may initiate a transaction to thepermissioned blockchain 304. In this example, the transaction can be adeploy, invoke, or query, and may be issued through a client-sideapplication leveraging an SDK, directly through an API, etc. Networksmay provide access to a regulator 306, such as an auditor. A blockchainnetwork operator 308 manages member permissions, such as enrolling theregulator 306 as an “auditor” and the blockchain user 302 as a “client”.An auditor could be restricted only to querying the ledger whereas aclient could be authorized to deploy, invoke, and query certain types ofchaincode.

A blockchain developer 310 can write chaincode and client-sideapplications. The blockchain developer 310 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 312 in chaincode, the developer 310 could use anout-of-band connection to access the data. In this example, theblockchain user 302 connects to the permissioned blockchain 304 througha peer node 314. Before proceeding with any transactions, the peer node314 retrieves the user's enrollment and transaction certificates from acertificate authority 316, which manages user roles and permissions. Insome cases, blockchain users must possess these digital certificates inorder to transact on the permissioned blockchain 304. Meanwhile, a userattempting to utilize chaincode may be required to verify theircredentials on the traditional data source 312. To confirm the user'sauthorization, chaincode can use an out-of-band connection to this datathrough a traditional processing platform 318.

FIG. 3B illustrates another example of a permissioned blockchain network320, which features a distributed, decentralized peer-to-peerarchitecture. In this example, a blockchain user 322 may submit atransaction to the permissioned blockchain 324. In this example, thetransaction can be a deploy, invoke, or query, and may be issued througha client-side application leveraging an SDK, directly through an API,etc. Networks may provide access to a regulator 326, such as an auditor.A blockchain network operator 328 manages member permissions, such asenrolling the regulator 326 as an “auditor” and the blockchain user 322as a “client”. An auditor could be restricted only to querying theledger whereas a client could be authorized to deploy, invoke, and querycertain types of chaincode.

A blockchain developer 330 writes chaincode and client-sideapplications. The blockchain developer 330 can deploy chaincode directlyto the network through an interface. To include credentials from atraditional data source 332 in chaincode, the developer 330 could use anout-of-band connection to access the data. In this example, theblockchain user 322 connects to the network through a peer node 334.Before proceeding with any transactions, the peer node 334 retrieves theuser's enrollment and transaction certificates from the certificateauthority 336. In some cases, blockchain users must possess thesedigital certificates in order to transact on the permissioned blockchain324. Meanwhile, a user attempting to utilize chaincode may be requiredto verify their credentials on the traditional data source 332. Toconfirm the user's authorization, chaincode can use an out-of-bandconnection to this data through a traditional processing platform 338.

In some embodiments, the blockchain herein may be a permissionlessblockchain. In contrast with permissioned blockchains which requirepermission to join, anyone can join a permissionless blockchain. Forexample, to join a permissionless blockchain a user may create apersonal address and begin interacting with the network, by submittingtransactions, and hence adding entries to the ledger. Additionally, allparties have the choice of running a node on the system and employingthe mining protocols to help verify transactions.

FIG. 3C illustrates a process 350 of a transaction being processed by apermissionless blockchain 352 including a plurality of nodes 354. Asender 356 desires to send payment or some other form of value (e.g., adeed, medical records, a contract, a good, a service, or any other assetthat can be encapsulated in a digital record) to a recipient 358 via thepermissionless blockchain 352. In one embodiment, each of the senderdevice 356 and the recipient device 358 may have digital wallets(associated with the blockchain 352) that provide user interfacecontrols and a display of transaction parameters. In response, thetransaction is broadcast throughout the blockchain 352 to the nodes 354.Depending on the blockchain's 352 network parameters the nodes verify360 the transaction based on rules (which may be pre-defined ordynamically allocated) established by the permissionless blockchain 352creators. For example, this may include verifying identities of theparties involved, etc. The transaction may be verified immediately or itmay be placed in a queue with other transactions and the nodes 354determine if the transactions are valid based on a set of network rules.

In structure 362, valid transactions are formed into a block and sealedwith a lock (hash). This process may be performed by mining nodes amongthe nodes 354. Mining nodes may utilize additional software specificallyfor mining and creating blocks for the permissionless blockchain 352.Each block may be identified by a hash (e.g., 256 bit number, etc.)created using an algorithm agreed upon by the network. Each block mayinclude a header, a pointer or reference to a hash of a previous block'sheader in the chain, and a group of valid transactions. The reference tothe previous block's hash is associated with the creation of the secureindependent chain of blocks.

Before blocks can be added to the blockchain, the blocks must bevalidated. Validation for the permissionless blockchain 352 may includea proof-of-work (PoW) which is a solution to a puzzle derived from theblock's header. Although not shown in the example of FIG. 3C, anotherprocess for validating a block is proof-of-stake. Unlike theproof-of-work, where the algorithm rewards miners who solve mathematicalproblems, with the proof of stake, a creator of a new block is chosen ina deterministic way, depending on its wealth, also defined as “stake.”Then, a similar proof is performed by the selected/chosen node.

With mining 364, nodes try to solve the block by making incrementalchanges to one variable until the solution satisfies a network-widetarget. This creates the PoW thereby ensuring correct answers. In otherwords, a potential solution must prove that computing resources weredrained in solving the problem. In some types of permissionlessblockchains, miners may be rewarded with value (e.g., coins, etc.) forcorrectly mining a block.

Here, the PoW process, alongside the chaining of blocks, makesmodifications of the blockchain extremely difficult, as an attacker mustmodify all subsequent blocks in order for the modifications of one blockto be accepted. Furthermore, as new blocks are mined, the difficulty ofmodifying a block increases, and the number of subsequent blocksincreases. With distribution 366, the successfully validated block isdistributed through the permissionless blockchain 352 and all nodes 354add the block to a majority chain which is the permissionlessblockchain's 352 auditable ledger. Furthermore, the value in thetransaction submitted by the sender 356 is deposited or otherwisetransferred to the digital wallet of the recipient device 358.

FIG. 4A illustrates a process 400A of querying a blockchain ledger via arange query according to example embodiments. Referring to FIG. 4A, asmart contract 444 running on a blockchain peer includes a statedatabase 446 (stored on a blockchain ledger). In this example, a loggingsystem 442 tracks users that are logged onto an enterprise network andrecords data about the user activities. The data may be stored on ablockchain managed by smart contract 444 including keys. The currentvalue of all keys may be stored by the smart contract 444 within thestate database 446.

In this example, the smart contract 444 has logic to count a number ofuser/employees that are logged into logging system 442 and log theresults on the blockchain ledger (state DB 446) every second of time.FIG. 4A illustrates an example of a communication sequence of the smartcontract 444 storing transactions to the state database 446, and theoccurrence of a phantom read error.

Because of network overhead, the time taken between proposal of atransaction and commit of that transaction can vary. In 401, a loggingsystem starts a first transaction at a time of 12:00:00. In 402, thesmart contract 444 counts the number of employees logged into the systemby a range query. Currently 6 employees are logged into the system. Therange query is then added to read set to check a phantom read error.

Meanwhile, in 403 a new user 440 logs onto the system. Now 7 employeesare logged onto the system. Furthermore, the smart contract 444 updatesthe blockchain ledger 446 with the new user information. This happensconcurrently between the endorsement and the validation of the firsttransaction received in 401. In 405, the logging system 442 triggers thestart of a next count transaction (transaction 2) at 12:00:01. The smartcontract 444 counts the number of employees logged in by a range query,in 406. The total count is 7. The range query added to read set fortransaction 2 to check a phantom read error. Here, a phantom error checkfor the second transaction is performed in 407 and it succeeds. Thus, in408, the second transaction is committed to the blockchain and the stateDB 446, and a success notification is sent in 409.

Meanwhile, the first transaction was delayed due to overhead. Here, in411, the smart contract 444 performs a phantom error check based on thecurrent state of the ledger (state DB 446). In this example, the currentnumber of users logged onto the system is recorded as 7, but the readset of the first transaction indicates the number of users is 6.Therefore, the phantom error check fails. Accordingly, in 412, the smartcontract 444 outputs a failure notification.

FIG. 4B illustrates a process 400B of querying an index structure 448 ontop of a blockchain ledger 446 according to example embodiments. In thisexample, the index structure 448 stores current keys of the blockchainledger in an index that logically resides above the state DB 446 of theblockchain ledger. In 421, the logging system 442 triggers a firsttransaction at 12:00:00. In 422, in response, the smart contract 444counts the number of employees logged into the system by querying theindex structure 448 without issuing a range query to the state DB 446.Currently 6 employees are logged into the system. This read is not addedto the read set for transaction 1 since no range query was used.Instead, the read set is created with only critical queries (not shownin this example).

In 423, a new user 440 logs into the system. Now 7 employees are loggedin. In this example, both the state DB 446 and the index structure 448are updated with the new key for the user 440.

Meanwhile, as in the case of FIG. 4A, the logging system 442 triggersthe start of a second transaction in 425. In this case, transaction 2starts at 12:00:01. In 426, the smart contract 444 counts the number ofemployees logged in by querying the index structure 448. The total countis 7. This read, however, is not added to the read set for transaction 2since no range query was used. In 427, the smart contract 444 performs aphantom error check based on the read set of the second transaction andthe check succeeds. In 428, the second transaction is added to theblockchain ledger and a success message is sent to the logging system442.

Meanwhile, just as in the example of FIG. 4A, the first transaction isdelayed. However, in 430, a phantom error check is performed andsucceeds because the non-critical transaction (employee/user count) wasnot added to the read set. Therefore, there is no need to perform aphantom error check on the employee count value read in 422. Instead,the first transaction is committed in 431, and a success message isprovided in 432.

FIG. 5 illustrates a method 500 of accessing an index structure on topof a blockchain ledger according to example embodiments. As anon-limiting example, the method 500 may be performed by a blockchainpeer, chaincode that is running on a blockchain peer, and the like,however embodiments are not limited thereto. Referring to FIG. 5, in510, the method may include storing an index structure that comprises anindex of keys from a blockchain ledger, where the keys are stored asnodes in the index structure. As an example, the index structure may bea binary tree, also referred to as a binary search tree. The tree mayinclude nodes which represent keys stored in the blockchain.

In some embodiments, the blockchain peer node may also build the indexstructure over time, as keys are added to the blockchain. For example,the index structure may be created and implemented within a smartcontract (deployed as chaincode) running on the blockchain peer node.The nodes may be ordered or otherwise connected to each other in anymanner desired. For example, the smart contract may include businessrules, methods, procedures, etc. for connecting the nodes/keys in theindex structure. When the index structure is a tree, such as a binarytree, the keys may be arranged as nodes in a hierarchical manner.

In 520, the method may include receiving a blockchain request for datastored on the blockchain ledger. For example, the blockchain request mayinclude a blockchain transaction which invokes a smart contract on ablockchain peer node. The blockchain request may be processed using oneor more queries to the blockchain ledger. In a traditional blockchain,these requests may be processed using range queries. However, in 530,the method may include reading a set of keys of a non-critical queryincluded in the blockchain request from the nodes in the index structureinstead of executing a range query on the blockchain ledger. Here, theblockchain request may include/need both critical and non-criticalqueries to the ledger. The blockchain peer may process the criticalqueries on the ledger. However, for non-critical queries, the blockchainpeer node may instead read the data from the index structure.

Furthermore, in 540, the method may include generating and storing aread set for the blockchain request which does not include values forthe set of keys of the non-critical query. Thus, a phantom read errorcan be avoided by processing non-critical queries on the index structureinstead of the blockchain ledger. Furthermore, the peer can avoidputting the keys read from the index structure within a read set of thesmart contract.

In some embodiments, the reading may include reading the set of keysone-by-one from the nodes in the index structure via a next function.Here, the next function may move to a next key/node in the indexstructure based on how the nodes are ordered by the smart contract whenthe smart contract is building the index structure. In some embodiments,the method may further include identifying a query of the blockchainrequest as the non-critical query when the query does not impact avalidity of the blockchain request. In some embodiments, the method mayinclude validating the blockchain request based on a previous read setfor the blockchain request which does not include the values for the setof keys read from the index structure. In some embodiments, the indexstructure may be implemented within logic of chaincode of a blockchainpeer node. In these examples, the keys in the index structure correspondto unique values stored on a blockchain of the blockchain ledger.

FIG. 6A illustrates an example system 600 that includes a physicalinfrastructure 610 configured to perform various operations according toexample embodiments. Referring to FIG. 6A, the physical infrastructure610 includes a module 612 and a module 614. The module 614 includes ablockchain 620 and a smart contract 630 (which may reside on theblockchain 620), that may execute any of the operational steps 608 (inmodule 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6B illustrates another example system 640 configured to performvarious operations according to example embodiments. Referring to FIG.6B, the system 640 includes a module 612 and a module 614. The module614 includes a blockchain 620 and a smart contract 630 (which may resideon the blockchain 620), that may execute any of the operational steps608 (in module 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6C illustrates an example system configured to utilize a smartcontract configuration among contracting parties and a mediating serverconfigured to enforce the smart contract terms on the blockchainaccording to example embodiments. Referring to FIG. 6C, theconfiguration 650 may represent a communication session, an assettransfer session or a process or procedure that is driven by a smartcontract 630 which explicitly identifies one or more user devices 652and/or 656. The execution, operations and results of the smart contractexecution may be managed by a server 654. Content of the smart contract630 may require digital signatures by one or more of the entities 652and 656 which are parties to the smart contract transaction. The resultsof the smart contract execution may be written to a blockchain 620 as ablockchain transaction. The smart contract 630 resides on the blockchain620 which may reside on one or more computers, servers, processors,memories, and/or wireless communication devices.

FIG. 6D illustrates a system 660 including a blockchain, according toexample embodiments. Referring to the example of FIG. 6D, an applicationprogramming interface (API) gateway 662 provides a common interface foraccessing blockchain logic (e.g., smart contract 630 or other chaincode)and data (e.g., distributed ledger, etc.). In this example, the APIgateway 662 is a common interface for performing transactions (invoke,queries, etc.) on the blockchain by connecting one or more entities 652and 656 to a blockchain peer (i.e., server 654). Here, the server 654 isa blockchain network peer component that holds a copy of the world stateand a distributed ledger allowing clients 652 and 656 to query data onthe world state as well as submit transactions into the blockchainnetwork where, depending on the smart contract 630 and endorsementpolicy, endorsing peers will run the smart contracts 630.

The above embodiments may be implemented in hardware, in a computerprogram executed by a processor, in firmware, or in a combination of theabove. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such thatthe processor may read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anapplication specific integrated circuit (“ASIC”). In the alternative,the processor and the storage medium may reside as discrete components.

FIG. 7A illustrates a process 700 of a new block being added to adistributed ledger 720, according to example embodiments, and FIG. 7Billustrates contents of a new data block structure 730 for blockchain,according to example embodiments. Referring to FIG. 7A, clients (notshown) may submit transactions to blockchain nodes 711, 712, and/or 713.Clients may be instructions received from any source to enact activityon the blockchain 720. As an example, clients may be applications thatact on behalf of a requester, such as a device, person or entity topropose transactions for the blockchain. The plurality of blockchainpeers (e.g., blockchain nodes 711, 712, and 713) may maintain a state ofthe blockchain network and a copy of the distributed ledger 720.Different types of blockchain nodes/peers may be present in theblockchain network including endorsing peers which simulate and endorsetransactions proposed by clients and committing peers which verifyendorsements, validate transactions, and commit transactions to thedistributed ledger 720. In this example, the blockchain nodes 711, 712,and 713 may perform the role of endorser node, committer node, or both.

The distributed ledger 720 includes a blockchain which stores immutable,sequenced records in blocks, and a state database 724 (current worldstate) maintaining a current state of the blockchain 722. Onedistributed ledger 720 may exist per channel and each peer maintains itsown copy of the distributed ledger 720 for each channel of which theyare a member. The blockchain 722 is a transaction log, structured ashash-linked blocks where each block contains a sequence of Ntransactions. Blocks may include various components such as shown inFIG. 7B. The linking of the blocks (shown by arrows in FIG. 7A) may begenerated by adding a hash of a prior block's header within a blockheader of a current block. In this way, all transactions on theblockchain 722 are sequenced and cryptographically linked togetherpreventing tampering with blockchain data without breaking the hashlinks. Furthermore, because of the links, the latest block in theblockchain 722 represents every transaction that has come before it. Theblockchain 722 may be stored on a peer file system (local or attachedstorage), which supports an append-only blockchain workload.

The current state of the blockchain 722 and the distributed ledger 722may be stored in the state database 724. Here, the current state datarepresents the latest values for all keys ever included in the chaintransaction log of the blockchain 722. Chaincode invocations executetransactions against the current state in the state database 724. Tomake these chaincode interactions extremely efficient, the latest valuesof all keys are stored in the state database 724. The state database 724may include an indexed view into the transaction log of the blockchain722, it can therefore be regenerated from the chain at any time. Thestate database 724 may automatically get recovered (or generated ifneeded) upon peer startup, before transactions are accepted.

Endorsing nodes receive transactions from clients and endorse thetransaction based on simulated results. Endorsing nodes hold smartcontracts which simulate the transaction proposals. When an endorsingnode endorses a transaction, the endorsing nodes creates a transactionendorsement which is a signed response from the endorsing node to theclient application indicating the endorsement of the simulatedtransaction. The method of endorsing a transaction depends on anendorsement policy which may be specified within chaincode. An exampleof an endorsement policy is “the majority of endorsing peers mustendorse the transaction”. Different channels may have differentendorsement policies. Endorsed transactions are forward by the clientapplication to ordering service 710.

The ordering service 710 accepts endorsed transactions, orders them intoa block, and delivers the blocks to the committing peers. For example,the ordering service 710 may initiate a new block when a threshold oftransactions has been reached, a timer times out, or another condition.In the example of FIG. 7A, blockchain node 712 is a committing peer thathas received a new data new data block 730 for storage on blockchain720. The first block in the blockchain may be referred to as a genesisblock which includes information about the blockchain, its members, thedata stored therein, etc.

The ordering service 710 may be made up of a cluster of orderers. Theordering service 710 does not process transactions, smart contracts, ormaintain the shared ledger. Rather, the ordering service 710 may acceptthe endorsed transactions and specifies the order in which thosetransactions are committed to the distributed ledger 720. Thearchitecture of the blockchain network may be designed such that thespecific implementation of ‘ordering’ (e.g., Solo, Kafka, BFT, etc.)becomes a pluggable component.

Transactions are written to the distributed ledger 720 in a consistentorder. The order of transactions is established to ensure that theupdates to the state database 724 are valid when they are committed tothe network. Unlike a cryptocurrency blockchain system (e.g., Bitcoin,etc.) where ordering occurs through the solving of a cryptographicpuzzle, or mining, in this example the parties of the distributed ledger720 may choose the ordering mechanism that best suits that network.

When the ordering service 710 initializes a new data block 730, the newdata block 730 may be broadcast to committing peers (e.g., blockchainnodes 711, 712, and 713). In response, each committing peer validatesthe transaction within the new data block 730 by checking to make surethat the read set and the write set still match the current world statein the state database 724. Specifically, the committing peer candetermine whether the read data that existed when the endorserssimulated the transaction is identical to the current world state in thestate database 724. When the committing peer validates the transaction,the transaction is written to the blockchain 722 on the distributedledger 720, and the state database 724 is updated with the write datafrom the read-write set. If a transaction fails, that is, if thecommitting peer finds that the read-write set does not match the currentworld state in the state database 724, the transaction ordered into ablock will still be included in that block, but it will be marked asinvalid, and the state database 724 will not be updated.

Referring to FIG. 7B, a new data block 730 (also referred to as a datablock) that is stored on the blockchain 722 of the distributed ledger720 may include multiple data segments such as a block header 740, blockdata 750 (block data section), and block metadata 760. It should beappreciated that the various depicted blocks and their contents, such asnew data block 730 and its contents, shown in FIG. 7B are merelyexamples and are not meant to limit the scope of the exampleembodiments. In a conventional block, the data section may storetransactional information of N transaction(s) (e.g., 1, 10, 100, 500,1000, 2000, 3000, etc.) within the block data 750.

The new data block 730 may also include a link to a previous block(e.g., on the blockchain 722 in FIG. 7A) within the block header 740. Inparticular, the block header 740 may include a hash of a previousblock's header. The block header 740 may also include a unique blocknumber, a hash of the block data 750 of the new data block 730, and thelike. The block number of the new data block 730 may be unique andassigned in various orders, such as an incremental/sequential orderstarting from zero.

The block metadata 760 may store multiple fields of metadata (e.g., as abyte array, etc.). Metadata fields may include signature on blockcreation, a reference to a last configuration block, a transactionfilter identifying valid and invalid transactions within the block, lastoffset persisted of an ordering service that ordered the block, and thelike. The signature, the last configuration block, and the orderermetadata may be added by the ordering service 710. Meanwhile, acommitter of the block (such as blockchain node 712) may addvalidity/invalidity information based on an endorsement policy,verification of read/write sets, and the like. The transaction filtermay include a byte array of a size equal to the number of transactionsthat are included in the block data 750 and a validation codeidentifying whether a transaction was valid/invalid.

FIG. 7C illustrates an embodiment of a blockchain 770 for digitalcontent in accordance with the embodiments described herein. The digitalcontent may include one or more files and associated information. Thefiles may include media, images, video, audio, text, links, graphics,animations, web pages, documents, or other forms of digital content. Theimmutable, append-only aspects of the blockchain serve as a safeguard toprotect the integrity, validity, and authenticity of the digitalcontent, making it suitable use in legal proceedings where admissibilityrules apply or other settings where evidence is taken in toconsideration or where the presentation and use of digital informationis otherwise of interest. In this case, the digital content may bereferred to as digital evidence.

The blockchain may be formed in various ways. In one embodiment, thedigital content may be included in and accessed from the blockchainitself. For example, each block of the blockchain may store a hash valueof reference information (e.g., header, value, etc.) along theassociated digital content. The hash value and associated digitalcontent may then be encrypted together. Thus, the digital content ofeach block may be accessed by decrypting each block in the blockchain,and the hash value of each block may be used as a basis to reference aprevious block. This may be illustrated as follows:

Block 1 Block 2 . . . Block N Hash Value 1 Hash Value 2 Hash Value NDigital Content 1 Digital Content 2 Digital Content N

In one embodiment, the digital content may be not included in theblockchain. For example, the blockchain may store the encrypted hashesof the content of each block without any of the digital content. Thedigital content may be stored in another storage area or memory addressin association with the hash value of the original file. The otherstorage area may be the same storage device used to store the blockchainor may be a different storage area or even a separate relationaldatabase. The digital content of each block may be referenced oraccessed by obtaining or querying the hash value of a block of interestand then looking up that has value in the storage area, which is storedin correspondence with the actual digital content. This operation may beperformed, for example, a database gatekeeper. This may be illustratedas follows:

Blockchain Storage Area Block 1 Hash Value Block 1 Hash Value . . .Content . . . . . . Block N Hash Value Block N Hash Value . . . Content

In the example embodiment of FIG. 7C, the blockchain 770 includes anumber of blocks 778 ₁, 778 ₂, . . . 778 _(N) cryptographically linkedin an ordered sequence, where N≥1. The encryption used to link theblocks 778 ₁, 778 ₂, . . . 778 _(N) may be any of a number of keyed orun-keyed Hash functions. In one embodiment, the blocks 778 ₁, 778 ₂, . .. 778 _(N) are subject to a hash function which produces n-bitalphanumeric outputs (where n is 256 or another number) from inputs thatare based on information in the blocks. Examples of such a hash functioninclude, but are not limited to, a SHA-type (SHA stands for Secured HashAlgorithm) algorithm, Merkle-Damgard algorithm, HAIFA algorithm,Merkle-tree algorithm, nonce-based algorithm, and anon-collision-resistant PRF algorithm. In another embodiment, the blocks778 ₁, 778 ₂, . . . , 778 _(N) may be cryptographically linked by afunction that is different from a hash function. For purposes ofillustration, the following description is made with reference to a hashfunction, e.g., SHA-2.

Each of the blocks 778 ₁, 778 ₂, . . . , 778 _(N) in the blockchainincludes a header, a version of the file, and a value. The header andthe value are different for each block as a result of hashing in theblockchain. In one embodiment, the value may be included in the header.As described in greater detail below, the version of the file may be theoriginal file or a different version of the original file.

The first block 778 ₁ in the blockchain is referred to as the genesisblock and includes the header 772 ₁, original file 774 ₁, and an initialvalue 776 ₁. The hashing scheme used for the genesis block, and indeedin all subsequent blocks, may vary. For example, all the information inthe first block 778 ₁ may be hashed together and at one time, or each ora portion of the information in the first block 778 ₁ may be separatelyhashed and then a hash of the separately hashed portions may beperformed.

The header 772 ₁ may include one or more initial parameters, which, forexample, may include a version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, duration, mediaformat, source, descriptive keywords, and/or other informationassociated with original file 774 ₁ and/or the blockchain. The header772 ₁ may be generated automatically (e.g., by blockchain networkmanaging software) or manually by a blockchain participant. Unlike theheader in other blocks 778 ₂ to 778 _(N) in the blockchain, the header772 ₁ in the genesis block does not reference a previous block, simplybecause there is no previous block.

The original file 774 ₁ in the genesis block may be, for example, dataas captured by a device with or without processing prior to itsinclusion in the blockchain. The original file 774 ₁ is received throughthe interface of the system from the device, media source, or node. Theoriginal file 774 ₁ is associated with metadata, which, for example, maybe generated by a user, the device, and/or the system processor, eithermanually or automatically. The metadata may be included in the firstblock 778 ₁ in association with the original file 774 ₁.

The value 776 ₁ in the genesis block is an initial value generated basedon one or more unique attributes of the original file 774 ₁. In oneembodiment, the one or more unique attributes may include the hash valuefor the original file 774 ₁, metadata for the original file 774 ₁, andother information associated with the file. In one implementation, theinitial value 776 ₁ may be based on the following unique attributes:

-   -   1) SHA-2 computed hash value for the original file    -   2) originating device ID    -   3) starting timestamp for the original file    -   4) initial storage location of the original file    -   5) blockchain network member ID for software to currently        control the original file and associated metadata

The other blocks 778 ₂ to 778 _(N) in the blockchain also have headers,files, and values. However, unlike the first block 772 ₁, each of theheaders 772 ₂ to 772 _(N) in the other blocks includes the hash value ofan immediately preceding block. The hash value of the immediatelypreceding block may be just the hash of the header of the previous blockor may be the hash value of the entire previous block. By including thehash value of a preceding block in each of the remaining blocks, a tracecan be performed from the Nth block back to the genesis block (and theassociated original file) on a block-by-block basis, as indicated byarrows 780, to establish an auditable and immutable chain-of-custody.

Each of the header 772 ₂ to 772 _(N) in the other blocks may alsoinclude other information, e.g., version number, timestamp, nonce, rootinformation, difficulty level, consensus protocol, and/or otherparameters or information associated with the corresponding files and/orthe blockchain in general.

The files 774 ₂ to 774 _(N) in the other blocks may be equal to theoriginal file or may be a modified version of the original file in thegenesis block depending, for example, on the type of processingperformed. The type of processing performed may vary from block toblock. The processing may involve, for example, any modification of afile in a preceding block, such as redacting information or otherwisechanging the content of, taking information away from, or adding orappending information to the files.

Additionally, or alternatively, the processing may involve merelycopying the file from a preceding block, changing a storage location ofthe file, analyzing the file from one or more preceding blocks, movingthe file from one storage or memory location to another, or performingaction relative to the file of the blockchain and/or its associatedmetadata. Processing which involves analyzing a file may include, forexample, appending, including, or otherwise associating variousanalytics, statistics, or other information associated with the file.

The values in each of the other blocks 776 ₂ to 776 _(N) in the otherblocks are unique values and are all different as a result of theprocessing performed. For example, the value in any one blockcorresponds to an updated version of the value in the previous block.The update is reflected in the hash of the block to which the value isassigned. The values of the blocks therefore provide an indication ofwhat processing was performed in the blocks and also permit a tracingthrough the blockchain back to the original file. This tracking confirmsthe chain-of-custody of the file throughout the entire blockchain.

For example, consider the case where portions of the file in a previousblock are redacted, blocked out, or pixelated in order to protect theidentity of a person shown in the file. In this case, the blockincluding the redacted file will include metadata associated with theredacted file, e.g., how the redaction was performed, who performed theredaction, timestamps where the redaction(s) occurred, etc. The metadatamay be hashed to form the value. Because the metadata for the block isdifferent from the information that was hashed to form the value in theprevious block, the values are different from one another and may berecovered when decrypted.

In one embodiment, the value of a previous block may be updated (e.g., anew hash value computed) to form the value of a current block when anyone or more of the following occurs. The new hash value may be computedby hashing all or a portion of the information noted below, in thisexample embodiment.

-   -   a) new SHA-2 computed hash value if the file has been processed        in any way (e.g., if the file was redacted, copied, altered,        accessed, or some other action was taken)    -   b) new storage location for the file    -   c) new metadata identified associated with the file    -   d) transfer of access or control of the file from one blockchain        participant to another blockchain participant

FIG. 7D illustrates an embodiment of a block which may represent thestructure of the blocks in the blockchain 790 in accordance with oneembodiment. The block, Block_(i), includes a header 772 _(i), a file 774_(i), and a value 776 _(i).

The header 772 _(i) includes a hash value of a previous blockBlock_(i-1) and additional reference information, which, for example,may be any of the types of information (e.g., header informationincluding references, characteristics, parameters, etc.) discussedherein. All blocks reference the hash of a previous block except, ofcourse, the genesis block. The hash value of the previous block may bejust a hash of the header in the previous block or a hash of all or aportion of the information in the previous block, including the file andmetadata.

The file 774 _(i) includes a plurality of data, such as Data 1, Data 2,. . . , Data N in sequence. The data are tagged with metadata Metadata1, Metadata 2, . . . , Metadata N which describe the content and/orcharacteristics associated with the data. For example, the metadata foreach data may include information to indicate a timestamp for the data,process the data, keywords indicating the persons or other contentdepicted in the data, and/or other features that may be helpful toestablish the validity and content of the file as a whole, andparticularly its use a digital evidence, for example, as described inconnection with an embodiment discussed below. In addition to themetadata, each data may be tagged with reference REF₁, REF₂, . . . ,REF_(N) to a previous data to prevent tampering, gaps in the file, andsequential reference through the file.

Once the metadata is assigned to the data (e.g., through a smartcontract), the metadata cannot be altered without the hash changing,which can easily be identified for invalidation. The metadata, thus,creates a data log of information that may be accessed for use byparticipants in the blockchain.

The value 776 _(i) is a hash value or other value computed based on anyof the types of information previously discussed. For example, for anygiven block Block_(i), the value for that block may be updated toreflect the processing that was performed for that block, e.g., new hashvalue, new storage location, new metadata for the associated file,transfer of control or access, identifier, or other action orinformation to be added. Although the value in each block is shown to beseparate from the metadata for the data of the file and header, thevalue may be based, in part or whole, on this metadata in anotherembodiment.

Once the blockchain 770 is formed, at any point in time, the immutablechain-of-custody for the file may be obtained by querying the blockchainfor the transaction history of the values across the blocks. This query,or tracking procedure, may begin with decrypting the value of the blockthat is most currently included (e.g., the last (N^(th)) block), andthen continuing to decrypt the value of the other blocks until thegenesis block is reached and the original file is recovered. Thedecryption may involve decrypting the headers and files and associatedmetadata at each block, as well.

Decryption is performed based on the type of encryption that took placein each block. This may involve the use of private keys, public keys, ora public key-private key pair. For example, when asymmetric encryptionis used, blockchain participants or a processor in the network maygenerate a public key and private key pair using a predeterminedalgorithm. The public key and private key are associated with each otherthrough some mathematical relationship. The public key may bedistributed publicly to serve as an address to receive messages fromother users, e.g., an IP address or home address. The private key iskept secret and used to digitally sign messages sent to other blockchainparticipants. The signature is included in the message so that therecipient can verify using the public key of the sender. This way, therecipient can be sure that only the sender could have sent this message.

Generating a key pair may be analogous to creating an account on theblockchain, but without having to actually register anywhere. Also,every transaction that is executed on the blockchain is digitally signedby the sender using their private key. This signature ensures that onlythe owner of the account can track and process (if within the scope ofpermission determined by a smart contract) the file of the blockchain.

FIGS. 8A and 8B illustrate additional examples of use cases forblockchain which may be incorporated and used herein. In particular,FIG. 8A illustrates an example 800 of a blockchain 810 which storesmachine learning (artificial intelligence) data. Machine learning relieson vast quantities of historical data (or training data) to buildpredictive models for accurate prediction on new data. Machine learningsoftware (e.g., neural networks, etc.) can often sift through millionsof records to unearth non-intuitive patterns.

In the example of FIG. 8A, a host platform 820 builds and deploys amachine learning model for predictive monitoring of assets 830. Here,the host platform 820 may be a cloud platform, an industrial server, aweb server, a personal computer, a user device, and the like. Assets 830can be any type of asset (e.g., machine or equipment, etc.) such as anaircraft, locomotive, turbine, medical machinery and equipment, oil andgas equipment, boats, ships, vehicles, and the like. As another example,assets 830 may be non-tangible assets such as stocks, currency, digitalcoins, insurance, or the like.

The blockchain 810 can be used to significantly improve both a trainingprocess 802 of the machine learning model and a predictive process 804based on a trained machine learning model. For example, in 802, ratherthan requiring a data scientist/engineer or other user to collect thedata, historical data may be stored by the assets 830 themselves (orthrough an intermediary, not shown) on the blockchain 810. This cansignificantly reduce the collection time needed by the host platform 820when performing predictive model training. For example, using smartcontracts, data can be directly and reliably transferred straight fromits place of origin to the blockchain 810. By using the blockchain 810to ensure the security and ownership of the collected data, smartcontracts may directly send the data from the assets to the individualsthat use the data for building a machine learning model. This allows forsharing of data among the assets 830.

The collected data may be stored in the blockchain 810 based on aconsensus mechanism. The consensus mechanism pulls in (permissionednodes) to ensure that the data being recorded is verified and accurate.The data recorded is time-stamped, cryptographically signed, andimmutable. It is therefore auditable, transparent, and secure. AddingIoT devices which write directly to the blockchain can, in certain cases(i.e. supply chain, healthcare, logistics, etc.), increase both thefrequency and accuracy of the data being recorded.

Furthermore, training of the machine learning model on the collecteddata may take rounds of refinement and testing by the host platform 820.Each round may be based on additional data or data that was notpreviously considered to help expand the knowledge of the machinelearning model. In 802, the different training and testing steps (andthe data associated therewith) may be stored on the blockchain 810 bythe host platform 820. Each refinement of the machine learning model(e.g., changes in variables, weights, etc.) may be stored on theblockchain 810. This provides verifiable proof of how the model wastrained and what data was used to train the model. Furthermore, when thehost platform 820 has achieved a finally trained model, the resultingmodel may be stored on the blockchain 810.

After the model has been trained, it may be deployed to a liveenvironment where it can make predictions/decisions based on theexecution of the final trained machine learning model. For example, in804, the machine learning model may be used for condition-basedmaintenance (CBM) for an asset such as an aircraft, a wind turbine, ahealthcare machine, and the like. In this example, data fed back fromthe asset 830 may be input the machine learning model and used to makeevent predictions such as failure events, error codes, and the like.Determinations made by the execution of the machine learning model atthe host platform 820 may be stored on the blockchain 810 to provideauditable/verifiable proof. As one non-limiting example, the machinelearning model may predict a future breakdown/failure to a part of theasset 830 and create alert or a notification to replace the part. Thedata behind this decision may be stored by the host platform 820 on theblockchain 810. In one embodiment the features and/or the actionsdescribed and/or depicted herein can occur on or with respect to theblockchain 810.

New transactions for a blockchain can be gathered together into a newblock and added to an existing hash value. This is then encrypted tocreate a new hash for the new block. This is added to the next list oftransactions when they are encrypted, and so on. The result is a chainof blocks that each contain the hash values of all preceding blocks.Computers that store these blocks regularly compare their hash values toensure that they are all in agreement. Any computer that does not agree,discards the records that are causing the problem. This approach is goodfor ensuring tamper-resistance of the blockchain, but it is not perfect.

One way to game this system is for a dishonest user to change the listof transactions in their favor, but in a way that leaves the hashunchanged. This can be done by brute force, in other words by changing arecord, encrypting the result, and seeing whether the hash value is thesame. And if not, trying again and again and again until it finds a hashthat matches. The security of blockchains is based on the belief thatordinary computers can only perform this kind of brute force attack overtime scales that are entirely impractical, such as the age of theuniverse. By contrast, quantum computers are much faster (1000s of timesfaster) and consequently pose a much greater threat.

FIG. 8B illustrates an example 850 of a quantum-secure blockchain 852which implements quantum key distribution (QKD) to protect against aquantum computing attack. In this example, blockchain users can verifyeach other's identities using QKD. This sends information using quantumparticles such as photons, which cannot be copied by an eavesdropperwithout destroying them. In this way, a sender and a receiver throughthe blockchain can be sure of each other's identity.

In the example of FIG. 8B, four users are present 854, 856, 858, and860. Each of pair of users may share a secret key 862 (i.e., a QKD)between themselves. Since there are four nodes in this example, sixpairs of nodes exists, and therefore six different secret keys 862 areused including QKD_(AB), QKD_(AC), QKD_(AD), QKD_(BC), QKD_(BD), andQKD_(CD). Each pair can create a QKD by sending information usingquantum particles such as photons, which cannot be copied by aneavesdropper without destroying them. In this way, a pair of users canbe sure of each other's identity.

The operation of the blockchain 852 is based on two procedures (i)creation of transactions, and (ii) construction of blocks that aggregatethe new transactions. New transactions may be created similar to atraditional blockchain network. Each transaction may contain informationabout a sender, a receiver, a time of creation, an amount (or value) tobe transferred, a list of reference transactions that justifies thesender has funds for the operation, and the like. This transactionrecord is then sent to all other nodes where it is entered into a poolof unconfirmed transactions. Here, two parties (i.e., a pair of usersfrom among 854-860) authenticate the transaction by providing theirshared secret key 862 (QKD). This quantum signature can be attached toevery transaction making it exceedingly difficult to tamper with. Eachnode checks their entries with respect to a local copy of the blockchain852 to verify that each transaction has sufficient funds. However, thetransactions are not yet confirmed.

Rather than perform a traditional mining process on the blocks, theblocks may be created in a decentralized manner using a broadcastprotocol. At a predetermined period of time (e.g., seconds, minutes,hours, etc.) the network may apply the broadcast protocol to anyunconfirmed transaction thereby to achieve a Byzantine agreement(consensus) regarding a correct version of the transaction. For example,each node may possess a private value (transaction data of thatparticular node). In a first round, nodes transmit their private valuesto each other. In subsequent rounds, nodes communicate the informationthey received in the previous round from other nodes. Here, honest nodesare able to create a complete set of transactions within a new block.This new block can be added to the blockchain 852. In one embodiment thefeatures and/or the actions described and/or depicted herein can occuron or with respect to the blockchain 852.

FIG. 9 illustrates an example system 900 that supports one or more ofthe example embodiments described and/or depicted herein. The system 900comprises a computer system/server 902, which is operational withnumerous other general purpose or special purpose computing systemenvironments or configurations. Examples of well-known computingsystems, environments, and/or configurations that may be suitable foruse with computer system/server 902 include, but are not limited to,personal computer systems, server computer systems, thin clients, thickclients, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputer systems, mainframe computersystems, and distributed cloud computing environments that include anyof the above systems or devices, and the like.

Computer system/server 902 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 902 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 9, computer system/server 902 in cloud computing node900 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 902 may include, but are notlimited to, one or more processors or processing units 904, a systemmemory 906, and a bus that couples various system components includingsystem memory 906 to processor 904.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 902 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 902, and it includes both volatileand non-volatile media, removable and non-removable media. System memory906, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 906 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)910 and/or cache memory 912. Computer system/server 902 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 914 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not shown and typically called a “hard drive”). Althoughnot shown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to thebus by one or more data media interfaces. As will be further depictedand described below, memory 906 may include at least one program producthaving a set (e.g., at least one) of program modules that are configuredto carry out the functions of various embodiments of the application.

Program/utility 916, having a set (at least one) of program modules 918,may be stored in memory 906 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 918 generally carry out the functionsand/or methodologies of various embodiments of the application asdescribed herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 902 may also communicate with one or moreexternal devices 920 such as a keyboard, a pointing device, a display922, etc.; one or more devices that enable a user to interact withcomputer system/server 902; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 902 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 924. Still yet, computer system/server 902 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 926. As depicted, network adapter 926communicates with the other components of computer system/server 902 viaa bus. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 902. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method,and non-transitory computer readable medium has been illustrated in theaccompanied drawings and described in the foregoing detaileddescription, it will be understood that the application is not limitedto the embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions as set forth and defined by thefollowing claims. For example, the capabilities of the system of thevarious figures can be performed by one or more of the modules orcomponents described herein or in a distributed architecture and mayinclude a transmitter, receiver or pair of both. For example, all orpart of the functionality performed by the individual modules, may beperformed by one or more of these modules. Further, the functionalitydescribed herein may be performed at various times and in relation tovarious events, internal or external to the modules or components. Also,the information sent between various modules can be sent between themodules via at least one of: a data network, the Internet, a voicenetwork, an Internet Protocol network, a wireless device, a wired deviceand/or via plurality of protocols. Also, the messages sent or receivedby any of the modules may be sent or received directly and/or via one ormore of the other modules.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a smartphoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms etc.) thereto.

What is claimed is:
 1. An apparatus comprising: a storage configured tostore an index structure that comprises an index of keys from ablockchain ledger, where the keys are stored as nodes in the indexstructure; and a processor configured to receive a blockchain requestfor data stored on the blockchain ledger, read a set of keys of anon-critical query included in the blockchain request from the nodes inthe index structure, and generate and store a read set for theblockchain request which does not include values for the set of keys ofthe non-critical query.
 2. The apparatus of claim 1, wherein the indexstructure comprises a binary tree in which the keys are arranged asnodes in a hierarchical manner.
 3. The apparatus of claim 1, wherein theprocessor is further configured to build the index structure based onkey values that are added to the blockchain ledger.
 4. The apparatus ofclaim 1, wherein the processor is configured to read the set of keysone-by-one from the nodes in the index structure via a next function. 5.The apparatus of claim 1, wherein the processor is further configured toidentify a query of the blockchain request as the non-critical querywhen the query does not impact a validity of the blockchain request. 6.The apparatus of claim 1, wherein the processor is further configured tovalidate the blockchain request based on a previous read set for theblockchain request which does not include the values for the set of keysread from the index structure.
 7. The apparatus of claim 1, wherein theindex structure is implemented within logic of chaincode of a blockchainpeer node.
 8. The apparatus of claim 1, wherein the keys in the indexstructure correspond to unique values stored on a blockchain of theblockchain ledger.
 9. A method comprising: storing an index structurethat comprises an index of keys from a blockchain ledger, where the keysare stored as nodes in the index structure; receiving a blockchainrequest for data stored on the blockchain ledger; reading a set of keysof a non-critical query included in the blockchain request from thenodes in the index structure; and generating and storing a read set forthe blockchain request which does not include values for the set of keysof the non-critical query.
 10. The method of claim 9, wherein the indexstructure comprises a binary tree in which the keys are arranged asnodes in a hierarchical manner.
 11. The method of claim 9, furthercomprising building the index structure based on key values that areadded to the blockchain ledger.
 12. The method of claim 9, wherein thereading comprises reading the set of keys one-by-one from the nodes inthe index structure via a next function.
 13. The method of claim 9,further comprising identifying a query of the blockchain request as thenon-critical query when the query does not impact a validity of theblockchain request.
 14. The method of claim 9, further comprisingvalidating the blockchain request based on a previous read set for theblockchain request which does not include the values for the set of keysread from the index structure.
 15. The method of claim 9, wherein theindex structure is implemented within logic of chaincode of a blockchainpeer node.
 16. The method of claim 9, wherein the keys in the indexstructure correspond to unique values stored on a blockchain of theblockchain ledger.
 17. A non-transitory computer readable mediumcomprising instructions, that when read by a processor, cause theprocessor to perform a method comprising: storing an index structurethat comprises an index of keys from a blockchain ledger, where the keysare stored as nodes in the index structure; receiving a blockchainrequest for data stored on the blockchain ledger; reading a set of keysof a non-critical query included in the blockchain request from thenodes in the index structure; and generating and storing a read set forthe blockchain request which does not include values for the set of keysof the non-critical query.
 18. The non-transitory computer readablemedium of claim 17, wherein the index structure comprises a binary treein which the keys are arranged as nodes in a hierarchical manner. 19.The non-transitory computer readable medium of claim 17, wherein themethod further comprises building the index structure based on keyvalues that are added to the blockchain ledger.
 20. The non-transitorycomputer readable medium of claim 17, wherein the reading comprisesreading the set of keys one-by-one from the nodes in the index structurevia a next function.